Drop on demand ink jet technology is widely used in the printing industry. Printers using drop on demand ink jet technology can use either thermal ink jet technology or piezoelectric technology. Even though they are more expensive to manufacture than thermal ink jets, piezoelectric ink jets are generally favored as they can use a wider variety of inks and eliminate problems with kogation.
Piezoelectric ink jet print heads typically include a flexible diaphragm and an array of piezoelectric elements (i.e., transducers or actuators) attached to the diaphragm. When a voltage is applied to a piezoelectric element, typically through electrical connection with an electrode electrically coupled to a voltage source, the piezoelectric element bends or deflects, causing the diaphragm to flex which expels a quantity of ink from a chamber through a nozzle. The flexing further draws ink into the chamber from a main ink reservoir through an opening to replace the expelled ink.
Increasing the printing resolution of an ink jet printer employing piezoelectric ink jet technology is a goal of design engineers. One way to increase the resolution is to increase the density of the piezoelectric elements.
To attach an array of piezoelectric elements to pads or electrodes of a flexible printed circuit (flex circuit) or to a printed circuit board (PCB), a quantity (i.e., a microdrop) of conductor such as conductive epoxy, conductive paste, or another conductive material is dispensed individually on the top of each piezoelectric element. Electrodes of the flex circuit or PCB are placed in contact with each microdrop to facilitate electrical communication between each piezoelectric element and the electrodes of the flex circuit or PCB.
As resolution and density of the print heads increase, the area available to provide electrical interconnects decreases. Routing of other functions within the head, such as ink feed structures, compete for this reduced space and place restrictions on the types of materials used. Methods for manufacturing a print head having electrical contacts which are easier to manufacture than prior structures, and the resulting print head, would be desirable.